This article will undertake an analysis of the decision-making process of the courts in patent eligibility cases decided within the identified ages or periods. The primary focus, particularly in the formative and formalist periods, will be on decisions of the Supreme Court because of its direct review of such cases during these periods. The analysis will be directed principally to the reasoning of the courts in reaching their decisions in order to test the hypothesis that patent law tracks the general law during these periods and the underlying jurisprudence is consistent with other areas of the law. In short, the reasoning process, rather than the outcome, is the important aspect of the various cases in the various periods rather than the outcome, i.e. whether this period happens to be pro or anti-patent in the cyclic pattern that is seen over time.

An attempt will be made to identify patterns in the various periods. It, of course, cannot be expected that only one particular style of reasoning will be found in any given period. But one could expect some dominance of a particular style to evolve. Once the formative, formalist and modern eras are reviewed in detail, some general and particular conclusions will be drawn concerning the consistency of patent law in the confines of the patentable subject matter issue with the jurisprudence of the general law of corresponding periods.